Last year my ipad 2 was broken and the digitizer was replaced by "professinal". Now it doesnt work in lines (from top to down) and i want to replace it so i searched it on ebay. I found oem digitizers 100$ and others for 30$ and i dont know which to buy because i dont want to spend a lot of money on it again! So culd you help me what is the difference between the 2 digitizers in quality??